The invention relates to a closed induction furnace for the melting and casting of substances. A crucible surrounded by an induction coil is housed for tilting about a first axis in a gas-tight furnace chamber which has a closable opening for transferring the melt to a receiving vessel.
The term "closed induction furnace," means a furnace of this kind whose furnace chamber can be operated either with a vacuum and/or with a shielding gas. It is also possible to employ the different types of operation successively in order to perform different alloying and/or refining operations.
U.S. Pat. No. 3,460,604 discloses tiltable crucibles surrounded by an induction coil housed in a stationary furnace chamber. This furnace chamber must then be made big enough so that the crucible, starting from its melting position with its axis perpendicular, can be tilted by an angle of decidedly more than 90 degrees, until it is completely emptied. This type of construction necessitates furnace chambers with a considerable internal capacity and therefore it requires either long evacuation periods and/or powerful pumps and/or large amounts of shielding gases. Since it is expedient first to evacuate furnaces operated under shielding gases so as to save on the relatively expensive noble gases, the furnace chambers must therefore withstand the pressure of the atmosphere against a vacuum, so that expensive and heavy furnace chambers are required.
The interior capacities of such furnace chambers become still larger when the vessel for receiving the poured metal, a casting mold, an ingot mold or a ladle is also housed in it (U.S. Pat. No. 2,788,270).
These disadvantages were recognized early, and a type of furnace was created in which the furnace chamber surrounds the crucible to a certain extent like a mantle, so that the furnace can be tipped as a whole (U.S. Pat. No. 3,529,069 and German Patent 35 30 471). Disadvantageous in this case are the large masses that have to be moved, and this movement must be performed as smoothly as possible to avoid any disturbance of the pouring process.
The problems, diametrically opposed to one another, increase disproportionately as the size of the charge increases, and with it the size of the crucible.
Another disadvantage of previously known solutions lies in the necessity of having to provide expensive systems for transferring the melt into other chambers if the pouring and solidification are to be performed in a vacuum and/or under shielding gas. In this case, again, the problems increase disproportionately as the charge weight increases.